Abstract: There has been a significant focus on data integration for a long time. Recently XML has become the de-facto standard for publishing and exchanging data on the Web. And researchers presented various integration schemes of XML data, but XML itself is not very appropriate for describing the global schema. One of the schemes which uses ontology to describe global schema gains our research interest. Because the original research work did not really present an algorithm to generate maximal query execution plan, after formalizing the scheme, a naive algorithm named NaiveMaxQEP to generate the maximal query execution plan is provided in this paper. And then an optimized algorithm OptMaxQEP is presented based on the assumption of limited number of incomplete roles in the global ontology. Finally, in order to support efficiency of distributed resource integration, an optimization algorithm NetOptQEP working on the generated maximal query execution plans to produce network-cost optimized plans is also presented.